1. Field of the Invention
This invention relates to a quantum box structure and a carrier conductivity modulating device and, more particularly, to a carrier conductivity modulating quantum device using quantum boxes (also called quantum dots).
2. Description of the Related Arts
As a future prospect of semiconductor devices, a positive use of interactions among electrons has begun to be entered into consideration. For one reason, improvements in quality of semiconductor crystals have made it possible to realize a low density of electric charges with a uniformity. For another reason, heterojunctions of compound semiconductors have made it possible to confine electric charges in a narrow region. From this viewpoint, coupled quantum dots arrays have attracted special interest recently.
The present Applicant formerly proposed, in Japanese Patent Application No. Hei 5-21982, a method for modulating movements of electrons among quantum dots in such a coupled quantum dots array by an external electric field, and further proposed, in Japanese Patent Application No. Hei 5-174774, an assembled quantum dots device using this method.
In these methods, however, correlative modulation of electrons in the quantum dots array by the external electric field was not sufficiently efficient.
On the other hand, there is a recent vigorous study on semiconductor devices using a quantum-mechanical tunnelling effect. Typical examples include resonant tunneling diodes using GaAs/AlGaAs heterojunctions, resonant tunnelling type hot electron transistors (RHET) using GaAs/AlGaAs heterojunctions, and others.
In conventional semiconductor devices using a quantum-mechanical tunnelling effect, the barrier height and the barrier width greatly affect the tunnelling effect, and therefore need their precise control. This requirement caused a difficulty in manufacturing conventional semiconductor devices using a quantum-mechanical tunnelling effect and in integrating the semiconductor devices.